<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <script src="../../js/vue.js"></script>
</head>

<body>
  <div id="demo">
    <h2>李四之前得名字{{userName}}</h2>
  </div>
  <script>
    var vm = new Vue({
      el: '#demo',
      data: {
        userName: '张三'
      }
    })
    console.log(vm);
    // let x = new Vue({
    //   el: '#demo',
    //   data() {
    //     return {
    //       userName: '张三',
    //     }
    //   }
    // })

  </script>
</body>

</html>